JP2009538032A - Method for configuring radio resources for effective and efficient transmission in a wireless communication system - Google Patents

Abstract

A method for transmitting data packets in an orthogonal frequency division multiplexing (OFDM) system is provided.
In a method for transmitting a data packet in an orthogonal frequency division multiplexing (OFDM) system, receiving feedback information from an access terminal (AT), a CP (cyclic prefix) and a data part based on the feedback information Data packet transmission comprising: configuring an indoor environment or outdoor environment data packet using at least one of a variable period and a variable number of CPs; and transmitting the configured data packet to an AT. Configure the method.
[Selection] Figure 1

Description

  The present invention relates to a method for transmitting data, and more particularly, to a method for configuring radio resources for effective and efficient transmission in a wireless communication system.

  In cellular communications, those skilled in the art frequently use the terms 1G, 2G and 3G. These terms indicate the cellular technology generation used. That is, 1G indicates the first generation, 2G indicates the second generation, and 3G indicates the third generation.

  1G shows an analog telephone system known as an AMPS (Advanced Mobile Phone Service) telephone system. 2G is commonly used to indicate a digital cellular system that has spread worldwide and includes CDMAOne, Global System for Mobile Communications (GSM), and Time Division Multiple Access (TDMA). The 2G system can support more users in a denser area than the 1G system.

  3G generally indicates a digital cellular system currently deployed. Although these 3G communication systems have some significant differences, they are conceptually similar to each other.

  In a recent wireless communication system, a user (or a mobile) can freely walk around while enjoying an undisturbed service. For this reason, it is important to develop a scheme and technology for improving the efficiency and effectiveness of communication system services under all kinds of different conditions and environments of the wireless system. Various methods, including reducing unnecessary signal transmissions, to promote more effective and efficient transmission and free up resources to address various conditions and environments and improve communication services used.

  The present invention relates to a method for configuring radio resources for effective and efficient transmission in a wireless communication system that can substantially eliminate one or more problems due to limitations and disadvantages of the prior art.

  An object of the present invention is to provide a method for transmitting data packets in an orthogonal frequency division multiplexing (OFDM) system.

  It is another object of the present invention to provide a method for allocating radio resources in an orthogonal frequency division multiplexing (OFDM) system.

  Other advantages, objects and features of the present invention are set forth in part in the following description, and in part will be obvious to those skilled in the art or may be learned through practice of the invention. The objects and advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

  In order to achieve the above objects and other advantages in accordance with the objects of the present invention, as a method of transmitting data packets in an orthogonal frequency division multiplexing (OFDM) system, receiving feedback information from an access terminal (AT); Configuring an indoor environment or outdoor environment data packet using at least one of a CP (cyclic prefix), a data portion variable period, and a variable number of CPs based on the feedback information; and the configured data Transmitting a packet to the AT.

  In another aspect of the present invention, as a method of allocating radio resources in an orthogonal frequency division multiplexing (OFDM) system, the radio resources are configured to correspond to a node tree, and each node is assigned to the node tree. Assigning to users, each user using together the assigned notes and one or more nodes derived from the assigned nodes, and if one or more nodes are not assigned from the node tree Assigning the one or more unassigned nodes to at least one of a regular data tone, a guard tone or a pilot tone.

  In another aspect of the present invention, as a method of allocating radio resources in an orthogonal frequency division multiplexing (OFDM) system, the radio resources are configured to correspond to a node tree, and each radio resource is assigned to a node of the node tree. Assigning, wherein the node is a tile, and assigning the one or more unassigned tiles to at least one of a regular data tone, a guard tone or a pilot tone if one or more tiles are not used. A method of including is provided.

  The foregoing general description and detailed description of the invention are exemplary and are provided to illustrate the invention.

  According to the present invention, a method for transmitting data packets in an orthogonal frequency division multiplexing (OFDM) system can be provided.

  In addition, according to the present invention, a method for allocating radio resources in an orthogonal frequency division multiplexing (OFDM) system can be provided.

FIG. 6 is an exemplary diagram illustrating a longer data symbol period. FIG. 3 is an exemplary diagram illustrating a superframe structure of FL and RL. FIG. 6 is another exemplary diagram illustrating a superframe structure of FL and RL. FIG. 3 is an exemplary diagram illustrating a tree structure for resource allocation.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or similar parts are denoted by the same reference numerals as much as possible.

  In data transmission, the transmitter and / or receiver environment affects the transmission. Environments are classified into two categories: indoor environments and outdoor environments.

  In an indoor environment, delay spread is generally small, and the transmitter and / or receiver are operating at low speed or stopped. Consequently, in this environment (eg, indoor environment), the length of orthogonal frequency division multiplexing (OFDM) CP (cyclic prefix) is reduced in that narrower tones (or subcarriers) are used.

  The shorter the CP per symbol, the more energy is used for data transmission due to the smaller CP overhead. That is, the total data transmission time is further increased by the use of narrower OFDM tones, resulting in a longer data symbol period.

  FIG. 1 is an exemplary diagram illustrating longer data symbol periods. Referring to FIG. 1, the previous OFDM has two CPs, and each CP has a length of x chips. Thereafter, there are data symbols having a length of 128 chips. In the new OFDM symbol, there is one CP with a length of x chips, followed by a data symbol with 256 chips. Here, the previous OFDM symbol (or upper symbol) is considered as the symbol design for the outdoor environment, and the new OFDM symbol (or lower symbol) is considered as the symbol design for the indoor environment.

  That is, the upper OFDM symbol requires two CPs over time period T, while the lower (new) OFDM symbol requires only one CP. This is an example in which the CP length is selected as x. Other CP lengths that can change the length or number of data chips may be used, and the CP length may be reduced relative to the indoor environment.

  Also, although the example of FIG. 1 uses 128 chips for the data portion of the upper (previous) OFDM symbol, other sample chip sizes may be used (eg, 256 chips). Further, the multiple need not be 2 as described above, and other multiples such as 3, 4 may be used.

  Due to the mobility of the user, the user frequently moves from the outdoor environment to the indoor environment, or moves from the indoor environment to the outdoor environment. In general, in cellular systems, OFDM numerologies are designed to optimize performance in outdoor environments. Other sets of formats or OFDM numerology are designed to be more effective for indoor use.

  As mobiles (or users) roam between indoor and outdoor environments, the OFDM symbol boundaries in indoor and outdoor formats are periodically aligned so that the frame / slot structure is synchronized to the two environments. The This method can eliminate delays for synchronization and acquisition of the target system when the mobile moves between the two environments. This method also facilitates transitions between the two environments and is suitable for two environments (eg, different formats are used for different interlaces in a time division multiplexing scheme). Useful for designing.

  For example, one interlace is used for indoor use, and the other interlace is used for outdoor use. That is, the subpackets for the indoor environment and the outdoor environment are interlaced. This is helpful at the boundary area between the indoor and outdoor cells. Also, a mix of interlaces (eg, indoor and outdoor interlacing) can be adapted depending on the traffic requirements between the indoor user and the outdoor user.

  The embodiments of the present invention describe an OFDM format set suitable for indoor use, whose symbol period is a multiple of the outdoor format. The symbol boundaries of both formats are periodically aligned so that the same frame / slot structure is used for both environments. Also, one system can temporally multiplex two forms of OFDM format using a unified frame / slot structure.

  A minimum Fast Fourier Transform (FFT) magnitude that corresponds to a sampling frequency that is greater than or equal to the system bandwidth is used to transmit and / or receive OFDM signals. For example, with a 1.68 MHz based clock, instead of the 2048 commonly used for such system bandwidths, outdoor deployment (or outdoor) for system bandwidths up to 1536 FFT size up to 20.16 MHz Environment). Hereinafter, other examples having different CPs and tone spacing will be described.

  The following description relates to OFDM symbol design and numerology associated with different symbol designs. For example, the design is based on 1.2288 MHz and 1.68 MHz clock (or chip) rates for outdoor environments. The format for the outdoor environment is based on conventional designs, and the format for the outdoor environment can have shorter CPs with narrower tone (or subcarrier) spacing. Therefore, CP overhead is reduced. That is, the CP overhead per slot / frame is reduced, so that the symbol period becomes twice the outdoor symbol period. Finally, the slot / frame structure is aligned for indoor and / or outdoor deployment (or environment).

  The following table shows various examples of OFDM symbol design numerology for indoor and outdoor environments. The actual OFDM symbol design numerology is not limited to the following example, and other numerology may be implemented.

Table 1 shows an example of OFDM symbol design numerology for outdoor deployment (or environment). Here, the chip (or clock) rate is based on 1.2288 MHz.

Table 2 shows an example of a new OFDM symbol design numerology for an indoor environment used with a 6.51 μs CP outdoor with a 1.2288 MHz based clock.

Table 3 shows an example of a new OFDM symbol design numerology for an indoor environment used with a 13.02 μs CP outdoor with a base clock of 1.2288 MHz.

Table 4 shows an example of a new OFDM symbol design numerology for an indoor environment used with a 19.53 μs CP outdoor with a 1.2288 MHz based clock.

Table 5 shows an example of a new OFDM symbol design numerology for the indoor environment used with a 26.04 μs CP outdoor with a 1.2288 MHz based clock.

Table 6 shows an example of OFDM symbol design numerology for an outdoor environment. Here, the chip rate is based on a 1.68 MHz clock.

Table 7 shows an example of a new OFDM symbol design numerology for the indoor environment. Here, the chip rate is based on a 1.68 MHz clock.

Table 8 shows an example of OFDM symbol design numerology for the outdoor environment. Here, the chip rate is based on a 1.2288 MHz clock.

Table 9 shows an example of OFDM symbol design numerology for an indoor environment used in conjunction with a 9.77 μs CP + W outdoor environment with a 1.2288 MHz based clock.

Table 10 shows an example of OFDM symbol design numerology for an indoor environment used in conjunction with a 16.28 μs CP + W outdoor environment with a 1.2288 MHz based clock.

Table 11 shows an example of OFDM symbol design numerology for an indoor environment used with a 22.79 μs CP + W outdoor environment with a 1.2288 MHz based clock.

Table 12 shows an example of OFDM symbol design numerology for an indoor environment used in conjunction with a 29.30 μs CP + W outdoor environment with a 1.2288 MHz based clock.

Table 13 shows an example of OFDM symbol design numerology for the outdoor environment. Here, the chip rate is based on a 1.68 MHz clock.

Table 14 shows an example of OFDM symbol design numerology for an indoor environment used with a 7.14 μs CP + W outdoor with a 1.68 MHz based clock.

Table 15 shows an example of OFDM symbol design numerology for indoor environments used with 11.90 μs CP + W outdoor with a 1.68 MHz based clock.

Table 16 shows an example of OFDM symbol design numerology for an indoor environment used with a 16.67 μs CP + W outdoor with a 1.68 MHz based clock.

Table 17 shows an example of OFDM symbol design numerology for an indoor environment used with a 21.43 μs CP + W outdoor with a 1.68 MHz based clock.

  The described format is intended for indoor environments but applies to any environment where delay spread is less than the CP period and low mobility.

  As described above, a variety of numerology applies to indoor and outdoor environments. In operation, numerology is configured by the location of the base station (or network). In particular, the base station (BS) or network first determines whether indoor or outdoor symbol numerology is based on channel quality information (CQI) and / or sector information (eg, CQI cover) from the access terminal (AT). Can be determined.

  If the BS or network determines that the AT is located in a CQI based indoor environment, the BS (or network) instructs the AT to use indoor numerology for the forward link (FL). That is, the BS transmits data using indoor numerology.

  Further, if the BS determines that the AT is located in an indoor environment based on CQI, the BS (or network) instructs the AT to use indoor numerology for the reverse link (RL). That is, the BS instructs the AT to use indoor numerology when transmitting data to the BS.

  Further, if the BS or network determines that the AT is located in an outdoor environment based on CQI, the BS (or network) instructs the AT to use outdoor numerology for the forward link (FL). . That is, the BS transmits data using outdoor numerology.

  Further, if the BS determines that the AT is located in an outdoor environment based on CQI, the BS (or network) instructs the AT to use outdoor numerology for the reverse link (RL). That is, the BS instructs the AT to use outdoor numerology when transmitting data to the BS.

  In indoor or outdoor numerology applications where the AT is indoors or outdoors, the AT can be moved from one location to another. That is, the AT can move from the indoor environment to the outdoor environment or from the outdoor environment to the indoor environment. In this case, a handoff (or handover) can occur between the environments.

  As described above, the superframe preamble is used in transmitting an instruction to use indoor or outdoor numerology from the BS (or network) to the AT. A super frame is composed of 25 physical frames and a preamble. Each physical frame is composed of 8 OFDM symbols (for example, 8 × 113.93 μs (6.51 μs CP) = 911.44 μs). The preamble includes 8 OFDM symbols. Also, the first RL physical frame is extended to align the FL and RL transmissions. FIG. 2 is an exemplary diagram illustrating a FL and RL superframe structure, and FIG. 3 is another exemplary diagram illustrating a FL and RL superframe structure.

  In order to embody indoor and outdoor operations, some physical frames are allocated to indoor operations. This information is included in the superframe preamble. Physical frames allocated for the indoor environment have a reduced CP period and / or different numerology.

  There are also two superframe structures: a superframe structure for the indoor environment and a superframe structure for the outdoor environment. Here, the superframes are aligned with each other. Both frame structures can share a common superframe preamble for reliable acquisition, but can have different physical frames with reduced CP duration and / or different numerology.

  In the OFDM system, some of the time and frequency resources are allocated to each other. In order to allocate part of the time and frequency resources and facilitate efficient resource allocation, all resources are divided into a plurality of blocks (tiles). That is, a plurality of blocks (tiles) are allocated to each other.

  In general, a block or tile is composed of 16 subcarriers and 8 symbols (eg, OFDM symbols). Blocks (or tiles) are subdivided into subtiles.

  Tables 18 through 21 show examples of tile designs with 32 tones (or subcarriers) fixed per tile. By having a fixed number of tones per tile, a uniform number of tones per tile (eg, 128 tones / tile) is provided independent of different subcarrier spacing and CP + W (window time). That is, the same resource partitioning method is used for all cases.

Table 18 shows an example of a tile design for 4.55 kHz subcarrier spacing with 32 tones fixed per tile.

Table 19 shows an example of a tile design for a 4.27 kHz subcarrier spacing with 32 tones fixed per tile.

Table 20 shows an example of a tile design for a 4.1 kHz subcarrier spacing with 32 tones fixed per tile.

Table 21 shows an example of a tile design for a 3.84 kHz subcarrier spacing with 32 tones fixed per tile.

  Each time is assigned to the user as a binary tree node as shown in FIG. FIG. 4 is an exemplary diagram illustrating a tree structure for resource allocation.

  Referring to FIG. 4, the nodes ((8,0) to (8,7)) show tiles for Table 18 having a bandwidth of 1.25 MHz. Nodes are assigned in various ways. For example, one node is assigned to one user, any number of nodes are assigned to each user, and node junk (ie, (4,1), (2,1) or (1,0) ) Is assigned to one user. Here, (4,1) means two consecutive tiles ((8,2) and (8,3)), and (2,1) is four consecutive tiles (( 8,4) to (8,7)), and (1,0) means that eight files of 1.25 MHz are allocated to one user.

  Also, any type of tree structure can be used to satisfy all numbers of tiles with a given time and frequency resource. That is, other types of tree structures are used to accomplish the same purpose. As described above, FIG. 4 shows an example of a tree structure (for example, a binary node tree).

  When the above binary tree structure (or any other tree structure) is used for resource allocation, there are extra (or residual) tiles and / or extra (or residual) tones. This is shown in the last two columns of Table 18 through Table 21 ("extra tile #" and "remaining tone #").

  These extra (or residual) tiles and / or tones are used as regular data tones, guard tones or pilot tones. In particular, extra (or residual) tones are used as pilot signals inserted between each tile.

  Based on the tile designs shown in Table 18 to Table 21, additional tile designs are implemented. These tile designs focus on reducing excess (or residual) tiles in a manner that controls or adjusts tile size.

  Tables 22 through 25 show examples of tile designs with different numbers of tones per tile. By having a different number of tones per tile, resources are allocated more efficiently and the number of extra (or residual) tiles is reduced.

Table 22 shows an example of a tile design for 4.55 kHz subcarrier spacing with 33 tones fixed per tile.

Table 23 shows an example of a tile design for a 4.27 kHz subcarrier spacing with 36 tones fixed per tile.

Table 24 shows an example of a tile design for a 4.1 kHz subcarrier spacing with 37 tones fixed per tile.

Table 25 shows an example of a tile design for 3.84 kHz subcarrier spacing with 40 tones fixed per tile.

  As shown in the table, depending on the bandwidth and / or tone spacing, extra (or residual) tiles are generated. A small number of extra or residual tiles (eg, 1 or 2 tiles) are used, for example, as guard tiles. In general, two tiles are used for guard tones with a 5 MHz bandwidth. Also, extra or residual tiles are used for data tones and / or pilot tones. These extra or residual tones are used in the same manner as regular data tones, guard tones and pilot tones inserted between each tile.

  Various changes and modifications can be made without departing from the scope of the present invention. Accordingly, the present invention covers the changes and modifications of the present invention provided within the scope of the appended claims and their equivalents.

Claims (20)

In a method for transmitting data packets in an orthogonal frequency division multiplexing (OFDM) system,
Receiving feedback information from an access terminal (AT);
Configuring an indoor environment or outdoor environment data packet using at least one of a CP (cyclic prefix), a data portion variable period, and a variable number of CPs based on the feedback information;
Transmitting the structured data packet to the AT.   The method of claim 1, wherein the feedback information is at least one of channel quality information and sector information.   The method of claim 1, wherein the data packet represents a plurality of physical frames and a preamble.   The method according to claim 3, wherein the preamble indicates whether the data packet is for the indoor environment or an outdoor environment.   The method of claim 1, wherein data packets for the reverse link and the forward link are periodically aligned.   The method of claim 1, wherein the configured data packet represents a time-multiplexed format of the indoor and outdoor environments.   The method of claim 1, wherein the configured data packet has a chip rate of 1.2288 MHz, 1.68 MHz or a multiple thereof.   The data packet transmission method according to claim 1, wherein the data packet configured for the indoor environment has a narrower tone spacing and a shorter CP than the data packet configured for the outdoor environment. In a method for allocating radio resources in an orthogonal frequency division multiplexing (OFDM) system,
Configuring the radio resource to correspond to a node tree;
Assigning a node to each user from the node tree, wherein each user uses together the assigned note and one or more nodes derived from the assigned node;
Allocating one or more unassigned nodes to at least one of a regular data tone, a guard tone or a pilot tone when one or more nodes are not assigned from the node tree.   The radio resource allocation method according to claim 9, wherein the radio resource is a tile.   The radio resource allocation method according to claim 10, wherein the tile includes 16 subcarriers and 8 OFDM symbols.   The method of claim 10, wherein the tile has a configurable number of subcarriers and OFDM symbols.   The radio resource allocating method according to claim 12, wherein the tile includes 32 or more subcarriers and 4 or more OFDM symbols.   The method of claim 9, wherein the OFDM system has variable subcarrier spacing and CP.   The radio resource allocation method according to claim 9, wherein the node tree is a binary node tree. In a method for allocating radio resources in an orthogonal frequency division multiplexing (OFDM) system,
Configuring the radio resource to correspond to a node tree;
Allocating each radio resource to a node in a node tree, wherein the node is a tile;
Allocating the one or more unassigned tiles to at least one of a regular data tone, a guard tone or a pilot tone when one or more tiles are not used.   The method of claim 16, wherein the tile is configurable.   The radio resource allocation method according to claim 17, wherein the tile includes 32 or more subcarriers and 4 or more symbols.   The method of claim 16, wherein the unused tiles are used as pilot tones inserted between the tiles.   The method of claim 16, wherein the node tree is a binary node tree.

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